1. Field of the Invention
The present invention relates to a heat exchanger having first and second header tanks and a plurality of flat tubes disposed in parallel with each other between the first and second header tanks. The heat exchanger is suitable for a condenser for condensing refrigerant.
2. Description of Related Art
JP-A-4-240398 proposes a heat exchanger which includes two tubular header tanks and a plurality of flat tubes. Each of the header tanks has a plurality of oval-shaped tube-insertion holes on a circumference surface thereof. Both ends of each flat tube are inserted into the tube-insertion holes so that the two header tanks and the flat tubes are integrally connected to be communicated with each other.
In the heat exchanger, to prevent fluid (e.g., refrigerant) from leaking from a joint portion between the header tanks and the flat tubes, each end of the flat tubes is inserted into the insides of the header tanks so that the flat tubes are firmly attached to the header tanks. Therefore, each outer dimension of the header tanks is made larger than each width of the flat tubes. Thus, the size of the header tanks becomes larger; and accordingly, the size of the heat exchanger also becomes larger. Further, because the heat exchanger can not be reduced in size, a volume of fluid flowing through the heat exchanger cannot be reduced.
As shown in FIG. 6, an another type heat exchanger is also known. In the heat exchanger, a first header tank 11 includes a first groove member 110 and a second groove member 111, and a second header tank 12 includes a first groove member 120 and a second groove member 121. The first groove members 110, 120 have a plurality of tube-insertion holes (not shown) into which flat tubes 14 are inserted. That is, in the heat exchanger, because the flat tubes 14 are inserted inside the first groove members 110, 120 through the tube-insertion holes, each width of the first groove members 110, 120 in a left-right direction in FIG. 6 is larger than each width of the flat tubes 14 as shown in FIG. 6. Thus, the width of the header tanks 11, 12 becomes larger relative to that of the flat tubes, and thereby increasing the size of the heat exchanger.